Industry Updates

EDGE, 3G, HSPA, LTE and Beyond

26 Nov 2011

EDGE vs. 3G

The critical difference between these two technologies is that EDGE (Enhanced Data rates for Global Evolution or
Enhanced Data for GSM Evolution), by definition, is an
enhancement to existing GSM networks, using existing GSM frequencies. 3G is
seen as a powerful driver for the development of terminals capable of full-web
browsing.

EDGE is often referred to
as a 2.75G network. It is a further step towards the capacities and
capabilities of 3G, offering data speeds that are required for music and
videos. EDGE does not, however, offer video telephony.

GSM, GPRS, EDGE, SMS and IM

Globally,
2G drove an explosion in mobile voice services, but it provided only limited
data capabilityin the order of 14Kbps or less than a dialup modem at the time.

The introduction of and growing interest in the World Wide Web fueled an
increasing demand for higher-speed access on mobile devices. While the
providers and standards groups were busy laying grand plans for
third-generation (3G) wireless to offer broadband services to mobile users, it
was still several years away in terms of technology and investment, so an
interim solution was needed.

GSM addressed this by coming up with General
Packet Radio Services (GPRS), with practical data rates up to 85Kbps, and
Enhanced Data for GSM Evolution (EDGE), with data rates up to 236Kbps (very
close to DSL and cable modems at the time). This required some new equipment to
be deployed by wireless operators and new phones from vendors. But it did not
require new frequency spectrum and was not a radical change in their operations
given the performance improvement.

In this same time period, Short
Message Service (SMS) was taking off in Europe, initially as a low-cost
communications alternative to a voice call, and then more as a cultural habit.
The same phenomenon would take place several years later in the United States
when a new generation of wireless users raised on instant messaging (IM)
started using mobile phones.

3G, HSPA, LTE, Mobile WiMAX and UWB

When 3G
standards development started in 1998, residential broadband penetration in the
world was relatively low. Speeds typically were in the 256 to 284Kbps range for
DSL and cable modems. As a result, the reference point for 3G was to design a
system that offered 128Kbps to moving cars, 384Kbps to mobile pedestrians, and
2Mbps to fixed users.

As fixed broadband penetration continued to advance
around the world, speeds above 1Mbps became commonplace and made a target like
384Kbps seem obsolete. In reality, 3G was unable to deliver even the target
levels of performance due to unexpected wireless performance issues following
launch.

As 3G
failed to meet the increasing demand for speed, High-Speed Packet Access (HSPA)
was introduced to enhance the performance of existing GSM-based cellular
systems. This offered the potential for much higher bandwidth for an individual
user (in excess of 7Mbps), but at the expense of reduced capacity for other
voice and data users.

As a result, operators are rolling out HSPA carefully in
their existing service areas and are developing HSPA+ to increase the speed and
improve the overall capacity per cell.

3G
managed to provide increased bandwidth (about 500Kbps, or less than half a
typical cable modem on average). But the improvements were too little to keep
pace with user expectations and the need to support bandwidth-hungry rich-media
applications. So in the interim, wireless operators have rolled out patchworks
of 3G and 3.5G capabilities such as HSPA, with speeds up to 14Mbps.

But these
technologies were inefficient stopgap solutions to a larger wave of demand for
high-quality mobile broadband services. Users are still unable to get broadband
connectivity and internetworking with other users and devices outside of a
small set of locations (hot spots) and situations.

Speeds
The following table compares the theoretical speeds available for EDGE, 3G and HSPA
technologies:

EDGE

3G

HSPA

Maximum download

236 Kbps

384 Kbps

1.8 Mbps

Maximum upload

Approximately 100 Kbps

64 Kbps

384 Kbps

Typically, actual maximum
speeds will be in the order of approx 80% of the maximum, whilst average speeds
will be in the order of 50% to 60% of the maximum. Factors affecting speeds
will be terminal (handset) capability, radio capability (the network), signal
strength (how far you are from a network tower), and how many concurrent users
are on the cell.

It is also important to
remember that network and handset technology is constantly improving and higher
speeds can / will become available over time.

Next Generation Standards

Next-generation
wireless standards have been on the drawing board since early 2000, but they
were given little attention because of the focus on rolling out 2.5G and 3G
services. Now that the realization is sinking in that a new solution is needed
to service the needs of future users, 4G has gained significant visibility
again.

LTE was
developed as a next-generation extension of GSM/UMTS. It supports up to 100Mbps
downloads and 50Mbps uploads to mobile users. It uses a technology called
Orthogonal Frequency Division Multiple Access (OFDMA) and smart antennas to
achieve much higher capacity than 3G systems.

Because over 80% of the world
uses GSM, they have a tremendous advantage to build on.

The
Mobile WiMAX standard followed a non-traditional development path more similar
to WiFi than cellular standards. The initial focus of WiMAX, starting in early
2000, was to create a viable fixed wireless alternative to cable modems and
DSL.

The original WiMAX standard was aimed at improving the economics and
performance of the previous proprietary approaches by creating an open standard
in partnership with key industry players (the WiMAX Forum).

The hope was to
achieve economies of scale. The original WiMAX standard (802.16a) was issued in
2003. But as the power of mobility became more apparent with the rapid growth
of 2G cellular, the WiMAX standards group and industry partners began to
develop a mobile version, WiMAX Mobile (802.16e), issued in December 2005.

The
basic standard supports mobile wireless broadband at speeds up to 70Mbps across
both licensed and unlicensed bands for a wide range of frequencies, providing
much more flexibility and deployment options than cellular.

However, questions
still surround WiMAXs range and ability to manage user handoffs versus more
proven cellular-based technologies. With Intels agreement to put WiMAX
chipsets into new laptops, the introduction of WiMAX-capable handsets from
Samsung, and commitments by service providers like Sprint, Clearwire, and
several international players, WiMAX has the makings of a formidable competitor
for future wireless broadband networks.

The key will be developing an ecosystem
of devices, like cameras and media players, and applications like mobile
entertainment and virtual conferencing, that leverage this network.

Comparison of LTE and WiMAX

LTE

WiMAX

Peak Download Speed

100Mbps

70Mbps

Peak Upload Speed

50Mbps

5 to 10Mbps

Average Range

30+ miles /48+ km

5+ miles /8+ km

LTE Advanced and 802.16m are
expected to push both of these technologies up to 1Gbps in the next iteration
of each standard. Given the huge uncertainty in deployment costs and actual
performance, it is tough if not impossible to pick a winner. It is possible
that a new disruptive solution will come from left field, such as Ultra
Wideband (UWB) to stake out the 4G opportunity.

Wireless vs wireline

Given
the information above it may sound logical that wireless channels would reach
the same level of speed as wireline broadband, however physical limitations
make this nearly impossible.

The speed of a given connection depends on the
amount of spectrum or frequency available, as well as the signal-to-noise
ratio.

As a point of comparison, fiber-optic lines have the most spectrum and
the lowest noise level. The signal is transmitted via light over glass, so very
little natural interference occurs.

The figure below shows the continuous gap
when comparing the progression of speeds in residential broadband channels
(from DSL to cable modem to fiber) to wireless broadband (from 1G to 4G).

Comparison of wireless and wireline
connection speeds

This is
primarily due to the fact that wireless transmits through an extremely variable
environment and is susceptible to the following degradations:

Multipath, in which multiple versions of the same signal
collide with buildings and other objects

Fading, in which the user moves behind objects or away
from the transmitter

Signal path loss due to atmospheric effects (e.g. water)

Interference from other wireless channels

Digitally enabled techniques such
as error detection and correction can combat some of these challenges, but they
cannot overcome the bandwidth and noise level advantages of wireline
connections.

Furthermore, the cellular environment comprises many areas of
coverage through which the user travels, entering and leaving coverage of the
various cells.

Intelligent mobility management techniques such as cell
selection and handover are used to mitigate the impacts of such user mobility,
but these also consume more resources, taking away from bandwidth to the user.

The true equalizer between wireline and wireless environments is mobility,
which makes the overall convenience and utility of wireless a winner.